The antibiotic knowledge survey of our new interns this week, showed that many were confused about which class vancomycin (a glycopeptide) fell into (30% thought it was an aminoglycoside). This is a potentially dangerous confusion as the dosing, side effects and monitoring all differ substantially between these classes:
| Aminoglycoside | Glycopeptide | |
| Indicative agents | Gentamicin | Vancomycin |
| Dosing | By ideal body weight (IBW) if actual weight > 20% over IBW | Actual weight ( see below) |
| Loading dose | No (higher dose in severe sepsis) | Yes |
| Monitoring | Not required for short course (3 daily dose) therapy | Yes (just prior to 4th dose) |
| Toxicity | Renal (cumulative)
Ototoxicity (idiosyncratic and cumulative) |
Renal (associated with sustained levels above 25mg/L)
Ototoxicity possible but rare |
| AIMED postings of relevance | Safe use of aminoglycosides | Dosing of vancomycin in obese patients |
The schema below worthy of further study! Particularly focus on betalactams, aminoglycosides, glycopeptides, sulphonamides, tetracyclines and quinolones to start with. This antimicrobial agent study proforma is a useful way to start documenting your knowledge.
An important aspect of antibiotic allergy surrounds the betalactam class – see these postings for useful allergy explanations from our experts.
Reference
The current Therapeutic Guidelines: Antibiotic is a useful starting point – look to the introductory chapter and the appendices on aminoglycosides and vancomycin. However, as a prescriber, you will need to know more than that !
AIMED - Let's talk about antibiotics 
Hi,
Thanks for the post!
Could you please provide the reference for the schema? Can’t quite read it!
Thanks so much
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AMG dosing weight is incorrect. Use Adjusted body weight if actual weight is > 120% of ideal body wt.
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